The rise of plastic packaging material closely relates to the change of general lifestyle. The use of light, convenient packaging to facilitate food storage and transportation, as well as increasing the shelf life of food has become very important due to the pressure from high population growth rate and food shortage. Although plastic packaging at present can satisfy these demand, the consumption of plastic has exceeded 160 million tons annually, within which 35% is used as packaging material. The treatment of waste from the packaging material imposes huge impact on the environment, so the recycling of plastic and the study of degradable plastic have become more and more important.
Biodegradable material has been generally defined as a material under sufficient water, oxygen, and suitable nutrients and temperature being able to decompose into carbon dioxide and water by microbes. Biodegradable material is a new type of polymer, which is characterized by the self-decomposition when its function completes. The bonding between these polymers decomposes into environmentally friendly compositions through biological processes. Biodegradable material is more friendly to the environment than conventional material. Generally speaking, the treatment and recycling for plastics used in disposable applications after use are not economic and impose greater impact on the environment. The treatment of contaminated plastics at present is nothing more than combustion or landfill, which invisibly increases the loading to the environment. Therefore, the development of biodegradable material has become a high-profile issue. Depending on the source of the material, biodegradable material can be divided into four categories: (1) biodegradable material based on polylactic acid; (2) biodegradable material based on polyester; (3) biodegradable material based on starch; and (4) biodegradable material based on polycaprolactone. Other natural materials such as soybean are also under development continually.
Although the biodegradable material at present is environmentally friendly, the structure of such material is hard to be modified, and their products after different kinds of fabrication processes have disadvantages of fragility, low heat-resistance, insufficient viscosity and so on. Therefore, the application of biodegradable materials is greatly limited, and the marketing products can only be used at low temperature. In view of this, the emphasis of future market demand will be focused on the environmentally friendly formula having increased functionalities of heat-tolerance, tenacity, viscosity and so on.